[NTG-context] MetaFun path joiners && and &&&& do not like single point paths

[Gavin via ntg-context <ntg-context@ntg.nl>]

Hi MetaFun fans,

Following a suggestion of Hans, I experimented with && and &&& and &&&& for joining paths in MetaFun. The joiner &&& produces one long path, but && and &&&& seem to produce a disconnected path which includes all the original paths. However, if one of the paths is a single point, then it connects it. MWE below.

I spotted this on my globes module, where we saw an extra line appear for a very specific orientation of the globe. I guessed that this orientation had an island right on the horizon, so that only one boundary point was visible, creating a singe point path for that island. I should probably fix my module so it doesn’t do that. However, it might be nice to have && and &&&& deal with this situation gracefully.

Gavin


\startMPpage
 path p[], q ;
 p1 = fullcircle scaled 3cm ;
 p2 = fullcircle scaled 2cm shifted (3cm,0) ;
 p3 = (3cm,2cm) ;
 q = for i = 1 upto 3 :
        p[i] &&
     endfor
     cycle ;
 draw p1 withpen pencircle scaled 2pt withcolor .7 ;
 draw p2 withpen pencircle scaled 2pt withcolor .7 ;
 draw p3 withpen pencircle scaled 2pt withcolor .7 ;
 draw q withcolor red ;
 eofill q withcolor 0.9 ;
 draw fullcircle scaled 6cm shifted (1.25cm,0) ;
\stopMPpage
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